Does Ultrasound Therapy Really Work?

Researchers are studying whether therapeutic ultrasound works as a treatment in physical therapy. Ultrasound machines may be used to improve circulation and tissue healing, but it’s unclear if it’s a useful component of injury recovery.

This article looks at ultrasound therapy in physical therapy and what the research says about its effectiveness.

Does Therapeutic Ultrasound Help?

Studies about using ultrasound to help speed healing are not so positive. There are many studies that compare ultrasound use to sham (fake) ultrasound. These studies indicate that people who receive an ultrasound for an injury do not have a speedier, healthier recovery or a better outcome.

For example, in a study on the use of ultrasound for knee arthritis, some of the study participants received the ultrasound treatment, while other study participants received sham ultrasound. There were no differences in the recovery of patients in either group.

Other studies have had mixed results. A 2020 review of studies into the effectiveness of therapeutic ultrasound for chronic pain found that therapeutic ultrasound was better at relieving knee pain than other methods. The review also looked at shoulder pain, however, and found that four out of seven studies showed that therapeutic ultrasound was inferior to other methods.

How Ultrasound Is Thought to Work

Therapeutic ultrasound has been used in physical therapy clinics for over 50 years. It provides heat to injured body parts that lie deep within your body that cannot be heated with a standard hot pack alone.

Inside an ultrasound machine, an electrical charge is applied to a crystal, creating a piezo-electric effect. This produces ultrasonic waves. These sound waves cannot be heard, but they are able to pass in through your skin and to tissues, producing microscopic gas bubbles near your injury that expand and contract rapidly. This process is called cavitation. Cavitation is thought to improve cellular function and speed up the healing process in your injured body part.

Heating Effects of Ultrasound

A published overview of therapeutic applications of ultrasound confirms that it certainly does heat your body parts when applied correctly. It also heats parts of your body that are deep and located outside of the reach of standard hot packs. So if you have an injury and your physical therapist feels that heat may be required to help your condition, ultrasound is a good choice to use.

Can Ultrasound Hurt?

Ultrasound is a pretty safe and innocuous treatment in physical therapy. There are some instances where ultrasound should absolutely not be used, such as over body parts with cancer and in young children, but for the most part, it can be used safely to heat-injured parts of your body.

Since many studies show that ultrasound offers very little to help speed healing in your injured body part, some physical therapists feel that ultrasound can “hurt” by making you feel like you need it to get better.

The Placebo Effect

Many physical therapists continue to use ultrasound and many feel that it adds positive outcomes in the treatment of many conditions. But is it really the placebo effect?

The placebo effect is a phenomenon where you perceive an improvement in your condition simply because something is being done to you. Your physical therapist tells you that ultrasound treatments can make you better, and therefore you start to feel better after receiving the treatments.

If your condition improves because of the placebo effect, that is fine. But some professionals argue that using the placebo effect in the treatment of conditions is unethical.

Bottom Line

In general, ultrasound is a safe treatment that has been used in physical therapy for many years. It provides heat to deep structures in the body, and it is thought that this heat helps improve that way that your body heals.

Studies may not really support the use of ultrasound in physical therapy. Still, it is commonly used and you may come across it if you go to physical therapy, so you should have some idea about what it is and what it can (and can’t) do.

If you do receive an ultrasound, you should also be actively involved in your physical therapy plan of care. You should make sure that your physical therapist helps you understand your condition and that he or she offers you strategies that you can apply to help improve your condition independently.

Summary

Evidence for the effectiveness of ultrasound therapy is mixed. Some studies have found that it can improve pain, while others have found no difference between the effectiveness of ultrasound and other kinds of treatment.

Ultrasound should not be used in certain situations, such as in very young children and people with cancer. For most people, however, it appears to be safe, and it may even make you feel better through the “placebo effect.”

A Word From Verywell

Ultrasound may be a treatment modality that you are exposed to during your physical therapy treatments. Research calls into question its efficacy, so if your PT does use it, be sure to understand the goals of treatment and the necessity of the treatment.